18B4.1 Safety risks

18B4.1.1 Explosions, fires and burns

As the popularity of e-cigarettes has increased, there have been growing reports of fires and burn injuries attributed to e-cigarette battery explosions.1-8An analysis of e-cigarette explosion and burn injuries presenting to US hospital emergency departments (EDs) between 2015 and 2017 concluded that past reports appear to substantially underestimate the actual number of these events. It estimated that there were 2035 presentations over this period—between 15 and 40 times more than previous estimates. The true number of injuries also likely exceeds these estimates, given that people with less severe injuries are less likely to present to an ED.9

A 2017 review of burns associated with e-cigarette batteries found that the most frequent sites of injury involved the lower extremities and hands. Nearly half of the reported incidences required surgical management as a result of the depth of injury.1An analysis of e-cigarette-related burns cases presenting to US emergency departments in 2016 found that most of the burns were thermal and occurred to the upper leg/lower trunk. Many occurred when the device was in users’ pockets.10There have also been case reports of such explosions causing fractures11and ocular injuries.12 A man was reportedly killed in late 2014 when a charging e-cigarette exploded and ignited his oxygen equipment.13

Following several fires, in 2015 the International Civil Aviation Organization prohibited airplane passengers and crew from carrying e-cigarettes and other battery-powered portable electronic smoking devices in checked baggage, and from recharging the devices in aircraft cabins.14

Although e-cigarette manufacturers have tended to attribute blame for explosions to the user for charging the devices improperly, a 2017 report from the US Fire Administration found that only 25 per cent of explosions occurred during the charging process. Sixty-two per cent of the devices exploded when being carried in a pocket or when they were actively in use. It notes that the shape and construction of e-cigarettes is itself problematic. Unlike other products such as mobile phones and laptops, e-cigarettes include cylindrical lithium-ion batteries installed in a cylindrical tube—one that is weakest at both ends. Battery failures generate increased pressure that “shoots” the batteries out of the tube like “rockets.” The report concludes that:

Lithium-ion batteries should not be used in e-cigarettes. While the number of batteries that explode and catch fire is statistically small, the catastrophic nature of the injuries that can occur warrants the use of another battery technology for e-cigarettes.15

18B4.1.2 Nicotine toxicity and accidental poisoning

The nicotine content of e-cigarettes typically ranges between 0 and 34mg/mL;16although several studies have reported discrepancies between labelled and measured nicotine content.17,18 At high enough doses, nicotine has acute toxicity.19Vaping is unlikely to cause nicotine overdose or intoxication, since the amount consumed and absorbed is quite low and comparable to smoking.20-22However, some e-liquid cartridges contain nicotine doses that are potentially toxic in adults and children if used in ways other than intended.23Intentional or accidental exposure to e-liquids can cause adverse health effects such as seizures, anoxic brain injury, vomiting, lactic acidosis, and death.24In recent years there have been increasing numbers of calls to poison information centres due to unintended ingestion of the e-liquid,25,26particularly by children,27-29with a baby in the US30and a toddler in Israel31reportedly dying after drinking from an e-cigarette refill bottle. The implementation of legislation requiring child-resistant packaging for liquid nicotine containers in the US appears to have reduced exposures to liquid nicotine among young children.32There have also been limited reports of intentional intoxication by injection and ingestion and a small number of suicide attempts associated with the cartridges.33-35E-cigarettes may also leak, presenting a hazard as nicotine can be absorbed through the skin.36

18B4.2 Abuse potential

18B4.2.1 Nicotine adddiction

Nicotine is among the most addictive of substances known.37,38 Although e-cigarette users appear to be less dependent on their product than comparable smokers,39-41most users still considered themselves to be addicted.40E-cigarettes may deliver systemic nicotine concentrations in a similar range to,16,42 or even in excess of,43those delivered by combustible cigarettes.

Nicotine absorption and dependency depends on how the e-cigarettes are used; types of puffs and intensity can determine the amounts of nicotine inhaled, in addition to the nicotine concentration of the e-liquid.44Some policy makers have suggested reducing the nicotine concentration in e-liquid to reduce the addictive potential of the products. For example, in the EU, nicotine content is limited to 20mg/ml. However, research suggests that among experienced vapers, such reductions do not translate to a reduction in nicotine absorption, possibly due to compensatory puffing.45,46

18B4.2.2 Vaping of other drugs

Along with nicotine, there are concerns that e-cigarettes are being used to consume cannabis, particularly among young people.47,48 Estimates of ever using an e-cigarette to use cannabis products in youth and young adult samples across North America range from 8 percent to 29 percent.24 Cannabinoid-enriched e-liquids are available for purchase online, or users can also reportedly download recipes and attempt to make their own cannabis e-liquid.49With the increasing legalisation of cannabis, the e-cigarette and cannabis industries and customer bases are likely to become increasingly intertwined.24

A review of the health effects of cannabis-vaping reached similar conclusions to the general literature: cannabis-vaping is likely less harmful than smoking traditional joints; cannabis e-liquids are unregulated and lack any toxicological and clinical assessment; both cannabis and nicotine pose risks to the neurodevelopment of young people, and also increase their risk of addiction; data on the potential health consequences of vaping cannabis for users and bystanders is extremely limited, and further research is urgently needed.49 Some have suggested that e-cigarettes show promise for the safe and efficient administration of medicinal cannabis.50

E-cigarettes can also be used to vape other types of drugs.49A review of e-cigarettes as an illicit drug delivery system found evidence of current use of e-cigarettes to vape almost all illicit drug types analysed. The authors highlighted that such use (via an easy to administer route and tool) may lead to higher levels and unusual patterns of drug use (continuous versus acute administration), potential increases in young adult use, addiction and toxicity, and paediatric accidental exposure.51Data on the prevalence of this type of use is limited, although an online survey of UK adults found that of the respondents that had used an electronic vaping device, more than one third (39.5%) had ever used them to vape recreational drugs, and more than one quarter (27.4%) reported current use. The most common drug vaped was cannabis (lifetime use 65.7%). Lifetime use was also high for vaping MDMA/’ecstasy’ (42.8%), cocaine powder (39.8%), mephedrone (30.9%), crack cocaine (30.5%), synthetic cannabinoid receptor agonists (28.4%), fentanyl (26.7%), heroin (25.8%), alpha-PVP (alpha-pyrrolidinopentiophenone)(25.8%), typtamines (25.4%), NBOMe (2, 5-dimethoxy-4-bromophenethylamine) (25%) and ketamine (24.6%).52

18B4.2.3 “Dripping”

E-cigarettes typically deliver e-liquid to the heating coil via saturated wicking material; however, “dripping” involves users putting a few drops of e-liquid directly onto an atomiser’s coil and then immediately inhaling the vapour that is produced.53Limited evidence suggests that dripping can expose users to high temperatures and toxic chemicals such as aldehydes.54

One study in Colorado found that among high school students who had ever used e-cigarettes, about one quarter (26.1%) had used the product for dripping.53However, the study was criticised for inadequately defining and measuring the concept.55Further research is needed regarding the use and health effects of dripping, both for consumer information and to inform regulations.56

Relevant news and research

For recent news items and research on this topic, click here.(Last updated November 2018)

19.U.S. Department of Health and Human Services. The health consequences of smoking: 50 years of progress. A report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014. Available from: http://www.surgeongeneral.gov/library/reports/50-years-of-progress/full-report.pdf.

20.Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, and Voudris V. Evaluation of electronic cigarette use (vaping) topography and estimation of liquid consumption: Implications for research protocol standards definition and for public health authorities’ regulation. International Journal of Environmental Research and Public Health, 2013; 10(6):2500–14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23778060

37.Royal College of Physicians of London. Nicotine addiction in Britain. A report of the tobacco advisory group of the royal college of physicians. London: Royal College of Physicians of London, 2000. Available from: http://www.rcplondon.ac.uk/pubs/books/nicotine/.

52.Blundell MS, Dargan PI, and Wood DM. A cloud on the horizon - a survey into the use of electronic vaping devices for recreational drug and new psychoactive substance administration. QJM, 2017. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29025078